The other political use of "doughnut" is for the practice of surrounding a speaker with enthusiastic supporters.

It first arose when Britain's House of Commons started being televised. Most of the chamber is empty most of the time, so when a minister stood up to speak, the cameras would reveal bare green benches. By doughnutting, it looks as though there's a crowd of enthusiasts shouting, "Hear, hear!"

Part of the agreement on televising parliament barred cameras from showing anything other than the speaker. So other than reporters commenting on the practice of doughnutting, viewers would not be aware that anything is amiss.